RU2375382C2 - Method of producing alkyd resin - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method is described for producing alkyd resin, involving acidolysis of plant oil with terephthalic acid at 260°C for 1 to 1.5 hours with subsequent polycondensation of the obtained product with glycerin. Terephthalic acid is a mixture of organic acids, which are an incompletely oxidised product of oxidising p-xylene during production terephthalic acid, with the following composition, wt %: terephthalic acid - 80 to 87, p-toluic acid - 8 to 15, benzoic acid - up to 0.4, 4-carboxybenzldehyde - up to 0.1, and water - the rest.

EFFECT: method shortens duration of the polycondensation stage and reduces loss resulting from distillation of the acid component, prevention of formation of residue in the end product.

1 cl, 4 tbl, 1 ex

Description

The invention relates to the synthesis of alkyd resins used as a binder in the manufacture of varnishes, primers, general-purpose enamels and other paints and varnishes.

A known method of producing alkyd resins by alcoholysis of vegetable oils with polyhydric alcohols, followed by the interaction of the products of alcoholysis with phthalic anhydride [1].

The disadvantage of this method is the long duration of the process, as well as the use of a basic catalyst, which requires additional purification steps to obtain a marketable product of the required quality.

It is known [2] that in order to intensify the process of producing alkyd resins, as well as to improve the technical properties of coatings based on alkyds, modifiers are used: maleic anhydride, rosin, benzoic acid, p-tert-butylbenzoic acid, and also described in [3] about α-toluic acid and o-toluic aldehyde.

The main disadvantage of these methods is the need for material costs for additional reagents. But even the introduction of additional reagents and a change in technological parameters does not lead to a decrease in the duration of the synthesis of traditional alkyd resins based on phthalic anhydride. The reason is the difficulty in removing the reaction water, since phthalic anhydride is easily sublimated at the temperature of the synthesis of resins (T _PL = 130 ° C per hect.), Which causes additional costs associated with cleaning the equipment and loss of the acid component.

There is another way to improve the synthesis of alkyd resins using new types of starting materials, such as isophthalic and terephthalic acids. A distinctive feature of these acids in comparison with phthalic anhydride is the high sublimation temperature (≥300 ° С), which allows them to be used to produce alkyd resins at a higher synthesis temperature with the reaction water being withdrawn by the fusion method, which (compared to the azeotropic reaction water) more simple in hardware design and maintenance, does not require large energy costs.

The main disadvantage of using acids in the synthesis of alkyd resins other than o-phthalic is the high process temperature (270-280 ° C) and their poor solubility in the reaction mixture, as a result of which part of the dibasic acid does not react [4].

A known method of producing modified alkyd resins [5] based on dicarboxylic acids and polyhydric alcohols by alcoholization of vegetable oils in the presence of alkaline catalysts and subsequent esterification of the resulting mixture of partial fatty acid esters with dicarboxylic acid in the presence of a catalyst.

As an esterification catalyst, 0.5-10% by weight of the reaction mixture of a quaternary ammonium salt is used. In order to intensify the process of decomposition of the catalyst, at the stage of esterification, 5-15 wt.% Formaldehyde is introduced based on the hydroxyl groups of pentaerythritol. This allows you to reduce the synthesis temperature to 260 ° C and reduce the duration of the second stage to 3 hours.

The disadvantage of this method is the additional cost of the catalysts, as well as the need for the introduction of formaldehyde to bind the esterification catalyst.

Closest to the claimed technical solution is the method [6], including acidolysis of vegetable oil with terephthalic acid and subsequent polyesterification with the introduction of the polyol. In this way, transparent alkyd resins are obtained.

The disadvantage of this method is that the duration of the polyesterification step is 4 hours, and the high cost of purified terephthalic acid does not make it possible to use it in industry.

The objective of the proposed method is to obtain an alkyd resin by the method of acidolysis using waste production of TPA.

The problem is solved by using as a dibasic acid a mixture of terephthalic acid with unoxidized intermediate products of p-xylene oxidation (a mixture of organic acids - JUICE), which is formed in the process of obtaining purified terephthalic acid and, in fact, is a waste product. JUICE has the following composition, wt.%:

terephthalic acid 80-87 p-toluic acid 8-15 benzoic acid up to 0.4 4-carboxybenzaldehyde up to 0.1 rest water

The invention is illustrated by the following example.

Oil and JUICE are charged into the flask. Gradually heated to 260 ° C, at this temperature, the oil is acidified with terephthalic acid until the acid number of the reaction mass reaches ~ 80 mg KOH / g. Then the temperature is reduced to 230 ° C and glycerin is charged for 40 minutes. Raise the temperature to 260 ° C, maintain the reaction mass to an acid number of not more than 15 mg KOH / g and a satisfactory viscosity of a 50% resin solution in a mixture of organic solvents.

Table 1 Alkyd Resin Formulations Components Recipe one 2 3 four Sunflower oil 54.3 56 - 46 Linseed oil - - 62 - Rosin - - - eleven* JUICE 32 thirty 26 28 Glycerol 13.7 fourteen 12 fifteen * - rosin is loaded with oil

table 2 Technological standards Indicators one 2 3 four Acidolysis temperature, ° С 260 260 260 260 Duration of acidolysis, h 1,5 one 1,5 1,5 Polycondensation temperature, ° С 260 260 260 260 The duration of the polycondensation, h 1.8 1,5 1.7 1.8 The viscosity of a 50% solution in a mixture of white spirit - xylene according to VZ-4, s 86 43 71 48 Acid number, mg KOH / g 15.0 10 15.0 9.6 Color of a 50% solution in a mixture of white spirit - xylene at MHI mg J _2/100 cm ³ 40 40 40 80

Upon completion of the synthesis and cooling of the alkyd to 180 ° C, a 50% solution of the resin in a white alcohol: xylene (3: 2) solvent mixture is prepared, its viscosity is measured using a VZ-4 viscometer, and the color is evaluated on an iodometric scale. Coatings for testing are prepared by applying to a metal plate a solution of alkyd resins in a mixture of solvents with a desiccant ZhK-1 (up to 3% by weight of varnish). After application by dipping, the varnish coatings are dried at a temperature of 20 ° C for 24 hours, after which they are tested.

Table 3 Alkyd Resin Coatings Indicators one 2 3 four The appearance of the film Transparent Transparent Transparent with insignificant. opalescence Transparent Drying up to st. 3 in 24 hours at 20 ° С complete complete complete complete The hardness of the coating according to the pendulum device type TML, conv. units 0.11 0.10 0.12 0.10 The elasticity of the film in bending, mm one one one one Film adhesion, points one one one one Resistance at 20 ° С to static action of water, h 48 48 48 48

Based on the obtained varnish No. 1, a primer according to the recipe GF-021 and white enamel - PF-115 were prepared. The test results of the obtained paints and varnishes given in table 4, meet the requirements of GOST.

Table 4 Testing results of paints and varnishes No. p / p Indicators Primer Enamel one. Film color Red brown shade - 2. Gloss of the film according to the photoelectric glossmeter,% - 61 3. Adhesion points one one four. Drying time to st.3 at 20 ° C 24 24 5. Mass fraction of nonvolatile substances,% 71 72 6. Conditional viscosity at 20 ° С according to VZ-4, s 90 one hundred 7. The elasticity of the film in bending, mm one one 8. Resistance at 20 ° C to static. exposure to water, h - 10 9. Resistance at 20 ° C to static. the impact of a 3% solution of sodium chloride, h 24 - 10. Resistance at 20 ° C to static. exposure to mineral oil, h 48 - eleven. Resistance at 20 ° C to static. exposure to transformer oil, h - 24 12. Resistance at 20 ° C to static. exposure to a 0.5% solution of detergent, min - fifteen

Thus, the described method for producing alkyd resins allows you to:

use RNS as a dibasic acid component instead of purified terephthalic acid, which significantly reduces, in comparison with the prototype, the cost of the final product;

reduce ~ 2 times the duration of the polyesterification stage;

reduce losses due to sublimation of the acid component, eliminate the formation of precipitate in the final product due to the complete conversion of the dibasic acid;

get the economic effect of exclusion from the process of obtaining alkyd resin catalysts and, accordingly, filtration under pressure of the finished product;

to obtain a transparent resin with a light Gliphtal chrominance indicator 40 mg J _2/100 cm ³ by reducing the duration of the synthesis.

Bibliography

1. Solomon D. Chemistry of organic film formers. M .: Chemistry, 1971 - 319 p.

2. Okhrimenko I.S., Verkholantsev V.V. Chemistry and technology of film-forming substances. - L .: Chemistry, 1978 - 392 p.

3. A.S. THE USSR. No. 1669926, 1991

4. Ind and End. Chem, 44, No. 7, 1952, 1595-1600.

5. A.s. CCCP No. 622822, 1978

6. US No. 2991259, 1961

Claims (1)

The method of producing alkyd resins, including acidolysis of vegetable oil with terephthalic acid followed by the interaction of the obtained product with glycerin, characterized in that a mixture of organic acids is used as terephthalic acid, which is an unoxidized product of the oxidation of p-xylene in the production of terephthalic acid, of the following composition, wt. %:
terephthalic acid 80-87 p-toluic acid 8-15 benzoic acid up to 0.4 4-carboxybenzaldehyde up to 0.1 water rest